There are various regions where people claim to be descendants of Oni, especially of Zenki and Goki.
They live in 大分県日田 Oita, Hita, 京都の八瀬村 Kyoto, Yasemura, 奈良県 Nara Gojo and Yoshino, 中津川 Wakayama, Nakatsugawa and other places.
All these regions are related to 修験道 Shugendo and Yamabushi mountain priest.
The descendants keep to themselves and have many rites pertaining to their Oni ancestors.

The name ONI might have been written like this : 隠（おん） ON.

Zenki and Goki are also alive in modern manga and anime games.鬼神童子 ZENKI

Zenki is a Japanese manga series written by Kikuhide Tani and illustrated by Yoshihiro Kuroiwa. It was serealized in the Shueisha publication, Monthly Shōnen Jump from 1992 to 1996.- - - More in the WIKIPEDIA !

Near the temple 安生寺 Ansho-Ji there are five families, who do NOT prepare chimaki 粽 ritual rice dumplings for the Boy's festival on May 5th and hishimochi 菱餅 red and white dumplings for the Girls's festival on May 3.
These families claim to be descendants of the Demons (Zenki and Goki). The Chimaki look like the tsuno 角 horns of an Oni and the Hishimochi look like oni no shita 鬼の舌 the tongue of an Oni, thus they feel it an insult against the ancestors to prepare them.
During the Setsubun rituals, they never chant
oni wa soto 鬼は外 but only fuku wa uchi 福は内.. Setsubun Rituals and Oni .

Families with the name 足立の安達姓 Adachi are descendants of Oni.
In the deep mountain there are three 古墳 Kofun mounds related to the Oni -
黒塚 Kurozuka, 鬼塚 Onizuka and 三ツ塚 Mitsuzuka.

The plain in front of the mounds is 安達ヶ原 Adachigahara. People claiming to be descendants from Oni might be
コロボックルの子孫 Korobokkuru descendants.. koropokkuru コロボックル "the little people" .
Ainu mythology, Hokkaido. 北海道のアイヌ伝説

.......................................................................yamanba 山姥 "mountain hag"
There lived an old woman in the village 笹楽 Sasara.
One day when she was eating chimaki 粽 ritual rice dumplings, she cut her lips. Since then the villagers of Sasara never prepare Chimaki for the Boy's festival rituals.

- - - literature : 大和宇智郡の鬼筋 // 大和に鬼の子孫がいる話

- quote - Mitsuzuka Mounded Tombs - Kofun
These are three square mounded tombs arranged from east to west on the south side of the Mausoleum of Empress Nakatsuhime.
From east, they are called Yashimazuka Mounded Tomb, Nakayamazuka Mounded Tomb, and Suketayama Mounded Tomb, respectively.
In 1978, large and small shura (wooden sleds) were discovered at the bottom of the surrounding moat between Yashimazuka Mounded Tomb and Nakayamazuka Mounded Tomb, which attracted wide attention from the public. - source :city.fujiidera.lg.jp/kanko -
大阪府藤井寺市岡1丁目1番1号 市役所6階63番窓口

. Yase Tenmangu 八瀬天満宮, Kyoto .
In ancient Japan, the term Yase Doji referred to the people who lived in the Yase district of Kyoto and worked for the area's Enryaku temple.
Despite their plebeian status, Yase Doji were prosperous and maintained strong connections with those in power, including emperors, aristocrats and shogun.
After the Meiji Era, they were even entrusted by the government to be the imperial koshi (palanquin) bearers.

滋賀県大津市葛川坊村 Shiga, Otsu, Katsuragawa
When priest 相応和尚 So-O looked for a pure place to practise austerities, he found the river Katsuragawa to be just right. He pleaded with the local Water Deity 思古淵神 Shikobuchi-shin and got the place. The deity also gave him two attendants, Joki and Joman.
Their descendants are living there now for more than 1000 years, as the two families of
葛野常喜家 Katsurano Joki and 葛野常満家 Katsurano Joman. They take part in many rituals.

Once the priest 相応和尚 So-O of the temple 葛川息障明王院 Katsuragawa Sokusho Myo-O In Myo-O In in Shiga found a 霊木 divine tree in the waterfall basin and carved this statue of Fudo Myo-O out of it.
葛川息障明王院 Temple Katsuragawa Sokusho Myo-O In. 建立大師相応和尚 Konryu Daishi So-O Kasho (833 - 918) .

. Kidoomaru 鬼童丸、鬼同丸 Kidomaru .
After Minamoto Raiko had killed the yokai Shuten Doji, all the girls he had kidnapped ("eaten") were set free to go home. But one had gone so out of her mind, she did not remember where she was from. She was pregnant and eventually gave birth to a baby with all teeth already there. This "Demon Child" 鬼童 Kido grew up and went to Kyoto, trying to kill the brother of Raiko. But he did not succeed and got caught himself.
Kidōmaru is known as both a robber and a magician ... He is the subject of legends of its own.

- quote -
Physical description:
Kidōmaru seated cross-legged on the head of a giant python, his hands clasped and two wrapped pine-sprigs in his mouth, a dirk has been driven into the head of the python, around which small snakes are writhing while four tengu watch.

"Kidōmaru is known as both a robber and a magician... The instruction that he receives here from the tengu can only be described as a sort of mystical experience involving self-purgation - he accesses a side of himself that he hitherto was not fully aware of. This Kidōmaru is not derived from the usual source, the Zen Taiheiki, rather he seems to be inspired by Takizawa Bakin's yomihon, Shitennō shōtō iroku (Strange Story of the Eradication of the Wicked Four Retainers,1806). In this yomihon, Kidōmaru competes in practicing magic with Hakamadare Yasuuke. Kidōmaru conjures up a poisonous serpent, whereas Yasuuke produces an eagle.

In this print the head of the giant python is almost as arresting as the countenance of Kidōmaru and provides a second strong focal point. The aomatsuba (wrapped pine sprigs) likewise command the viewer's attention, as do other elements such as the flames and the small writhing snakes. The colours in this print are riveting in their bold juxtaposition of blue and red.

There are two types of tengu, one is winged but has a human face with a very long nose (yamabushi or 'mountain priest' tenfu), the other has a bird's head and a strong, curved beak (karasu or 'crow' tengu). Four of the latter type inhabit the bottom section of this image."
Quoted from: Japanese Warrior Prints 1646-1905 / by James King and Yuriko Iwakiri, p. 269. - source : woodblockprints.org